Diabetes imposes a tremendous burden of morbidity and mortality on postmenopausal women. It is associated with a three- to nine-fold increase in risk of myocardial infarction (MI), an eight-fold increase in risk of peripheral vascular disease, and a threefold increase in risk for cardiovascular mortality. Observational studies indicate that hormone replacement therapy (HRT) reduces the risk of coronary heart disease (CHD) in postmenopausal women by 50 percent, while the effect of HRT on lower extremity peripheral arterial disease is unknown. The effects of HRT on CHD in women with diabetes have not been evaluated. The purpose of this case-cohort study is to examine the association between postmenopausal HRT (estrogen alone or with progestin) and CHD (nonfatal MI and fatal CHD) in postmenopausal women with Type II diabetes. Secondary outcomes include lower extremity amputations and all-cause mortality. The investigators state that a unique opportunity is available to conduct this study due to automated databases at Group Health Cooperative, a health maintenance organization in western Washington with over 500,000 members, including approximately 7,000 women with Type II diabetes. Women aged 45 to 80, with incident or prevalent Type II diabetes between 1986 and 1990, will be identified using criteria established for an ongoing study on management and outcomes in diabetics. From this cohort an age-stratified random sample of 1,500 women will be selected for the sub-cohort. These women plus those with the outcomes of interest (nonfatal MI and fatal CHD; lower extremity amputations; or death between cohort entry and September, 1998 [8 to 12 years follow-up]) will comprise the analytic cohort. Medical records will be reviewed to confirm eligibility and outcomes as well as to collect data on medical history, demographic characteristics and confounding variables. HRT use will be determined from computerized pharmacy records. Data will be analyzed using descriptive statistics, categorical survival methods, and Cox regression, applying methods specific to the case-cohort study design. The investigators state that this study will extend knowledge regarding the safety and efficacy of HRT in a subgroup of women at high risk for cardiovascular complications.